Etching machine



June 30,1942. R. A. ER; l 2,288,128

ETCHING MACHINE Filed July 24, 1941 2 Sheets-Sheet l lNVE'NTR F4 Man?Hija/212551Z, @-31 B z Z ATTORN EYS.

June 30, `1942.

R.A.VERz

ETGHING MACHINE 2 'sheets-sheet 2 Filed July 24, 1941 gli Y'INVENTORsdpfan] H/erf ATT RNEYS..

Patented June 30, 1942 NETE-B STATES PATENT @FFICE "Claims The presentinvention relates to improvements in etching machines wherein the acidor etching solution is distributed over the surface of the plate to beetched in such a manner as to provide a uniform covering of the surfaceto be etched.

An` object of thev invention is to lprovide an improved etching machinewherein the acid or etching solution is vagitatedand distributed overthe surface'of the plate to be etched, while the plate to be etched` ismoved relative to said acid or etchingsolution in such a manner that auniform distribution of the acid or etching solution over theface of theplate is effected` Another object of the present invention is to providean etching machine of anv improved and novel construction and inwhichtheretching acid or-solution is delivered to the face of the plate to beetched under pressure and is drawn away from the surface of the platebya suction and thereby removing the exhausted vacid orV etching:solution and taking with it the etched portions of the plate so as toprovide a clean etching' of the surface and a continual removal of saltsformed by the action of the acid or etching solution on the surface ofthe plate.

Another object of the present invention is to provide an improvedetching machine. which is of a relativelyV simple construction but whichis eiicient and economical'in operation and` produces improved-resultsin the mechanical etching of a photoengraved plate.

A further object of the present invention is to provide an etchingmachine in which provision is'made for theV agitation of the acid oretching solution in a tank in such a manner as to create a continuousflow in such tank in. a direction generally verticalto the face of theplate to be etched and at the Sametime moving the plate horizontallyrelative to the acid or etching solution in the tank, the plate at alltimes having its surface to be etchedsubmerged in the acid or etchingsolution in such vat or tank.

The above and'other objects and advantages of the invention will appearfrom` the following description and appended claims when considered inconnection with. the accompanying drawings forming a part of Vthisspecication wherein like reference characters designate correspondingparts in the several views.

A machine embodying the present invention is shown in the accompanyingdrawings, in which Fig. 1 is a view in perspective of an etching machineembodying the present invention.

Fig. 2 is a plan view of the machine shown in Fig. 1.

Fig. 3 is a vertical section taken substantially on the line 3 3 of Fig.2,1ooking in the direction of the arrows.

Fig. 4 is a horizontal section taken substantially on the line 4 4 ofFig. 3 looking inl the direction of the arrows.

Fig. 5 is a fragmentary sectional View taken substantially on the line 55 of Fig. 3 looking in the direction of the arrows.

Fig. 6 is a View taken along the line 6 6 of Fig. 1 looking in thedirection of the arrows.

Fig. 7 is a plan View taken substantially on the line 1 1 of Fig. 5looking in the direction of the arrows.

Fig. 8 is a sectional view taken substantially on the line 8 8 of Fig.'7.

Fig. 9 is a fragmentary/*plan taken of the line 9 9 looking in thedirection of the arrows of Fig. 5.

Fig. 10 is an enlarged fragmentarysection of the perforated grill orplunger taken on the line Iii-IU looking in the direction of the arrowsof Fig. 4.

Fig. 11 is a view in perspective of la plate etched by the etchingmachine of the present invention. t

Fig. 12 is an enlarged fragmentary section taken substantially on theline |2 |2.looking in the direction ofthe arrows of Fig. 1l.

Before explaining in detail the present invention it is to be understoodthatV the invention is not limited inY its application to the details ofconstruction and arrangement of parts illustrated in the accompanyingdrawings, since the invention is capable of other embodiments and ofbeing'practiced or carried out in various ways. Also it is to beunderstood .that the phraseology or terminology employed herein is forthe purpose of description and not of limitation.

Briefly, the preferredv embodiment of the present invention may be saidto consist in the provision of a receptacle for the etching solution, inwhich receptacle isV provided a movable grill whichV acts as aplunger,and moves vertically Within the Vat or tank. V'I'his grill, Inovingvertically in the tank; keeps the etching acid or solution incirculation and at Vthe same time creates currents within the materialso that the etching acid or solution is at all times delivered to theface of the plate to be etched under pressure .as-a result of themovement of the plunger downward from the plate and is drawn away fromthe face of the plate -as a result of the movement of the plunger in theopposite direction. During the time that the plunger is movingvertically within the tank of acid or etching solution, the plate ismoved horizontally in the tank. It has been found preferable that themovement of the plate should be at a different rate from the rate ofmovement of the grill or perforated member in the tank, since in thisWay different surfaces of the plate to be etched are brought intoposition relative to the currents of etching acid or solution so thatall portions of the face of the plate are subjected uniformly to theaction of the etching acid or solution.

Referring now to the drawings, and particularly to Figs. l, 3 and 5thereof, the numeral20 designates a tank or vat for containing theetching acid or fluid. A conventional form of acid used, for example, inthe etching of copper plates is perchloride of iron. It is essential,therefore, that the tank or vat 29 as Well as all parts of the apparatuswhich come in contact with the etching acid or fluid should be treatedso as to resist the action of the etching acid. I have found that awooden construction covered with rubber or asphaltum is satisfactory forthis purpose. Since the machine is intended to be used with etchingacids or fluids, it is important that all portions of the apparatuswhich come in contact with the acid should be similarly treated.

In order to prevent splashing of the acid and to have the machineenclosed during its operating cycle, a cover 2| which extends over theplateholder carrier 45 .is provided. The plateholder 48 is mounted forhorizontal movement in the tank and this movement is effected by thepivoted levers 22 which are connected with the cross shaft 23 (Fig. 3)which in turn is connected with the connecting rod 24 attached to thecrank 25 which is driven through the meshed gears 26 and 21 from therotatable shaft 28. The rotatable shaft 28 is driven by the motor 29through the motor pulley 3|), the belt 3| and the shaft pulley 32mounted on the shaft 28. Movement of the cross shaft 23 causes pivotingof the levers 22 about the pivot points 33 and this motion istransmitted to the cross pin 34 and the link 35 which is connected tothe lug 36 on the plateholder 48. It is to be understood that the samemechanism is provided on each side of the plate holder but that otherways of moving the plate holder horizontally in the tank 20 may be usedif desired. Where the duplicate parts appear on opposite sides of theapparatus shown in the drawings, similar numbers have been used and areused throughout the present specification.

The etching acid or other fluid inside the tank is agitated by theperforated plunger 31 which is mounted for vertical movement in the tank20. The perforated plunger 31 preferably consists of a frame 43 and aplurality of cross members 44 which, as shown in the present drawings(Fig. 4), are preferably placed diagonally to the frame 43 and cross oneanother to form a plurality of substantially diamond shaped or squareperforations between` the respective strands. One form of such materialwhich is satisfactory for the present purpose is a perforated steelplate which is coated with an acidproofed material such, for example, asthe rubber coating 45 (Fig. 10). The perforated plunger 31 is movedvertically in the tank 20 by the arms 38 which extend vertically abovethe surface of the frame 43 and are connected through blocks 39 withScotch yokes 4|! which are movable vertically in ways or guides 4| (Fig.1). It is understood that arms 38, blocks 39, Scotch yokes 48 and waysor guides 4| are provided on each side of the apparatus as here shown.The Scotch yokes 40 are driven from the rotatable shaft 28 by cams 42 asshown in Fig. 6.

I have found that it is desirable in a machine embodying the presentinvention to move the plateholder 48 in a horizontal direction at adifferent speed from the speed employed in moving the plunger 31 in thevertical direction. Thus, the pulleys 30 and 32 and the gears 26 and 21are selected so that the plateholder moves at a different speed from thespeed of movement of the plunger 31. In this Way the formation ofstreaks on the surface of the etched plate is avoided since differentportions of the surface of the plate 49 are constantly brought intoposition above the perforations in the plunger 31. I have found that ifthe two move at the same speed the same portion of the plate will bebrought into position above the same portion of the perforated plunger31 during each cycle of operation and that this tends to cause someportions of the plate to be etched more deeply than others, leading toan inferior etching of the plate since the deeper portions show up asstreaks in the nished etched plate.

The carrier 46 for the plateholder 48 is supported on a plurality ofrollers or other antifriction supports 41 which are secured to the tank.The rollers 41 are preferably formed of acid-proof material such as hardrubber or the like or they may be formed of other types of material andtreated so as to prevent their disintegration and deterioration in theetching acid. The plate 49 to be etched is held in the plateholder 48 bya plurality of adjustable clamps 5U (Figs. '7 and 8) which may beadjusted in such a way as to accommodate different sizes of plates inthe plate carrier.

In order to prevent surging of the etching acid or fluid in the tank,the bottom of the tank is constructed as shown in detail in Fig. 9 witha plurality of spaced and angularly disposed baiiie members or ribs 5|so that the tank bottom, as shown, contains a plurality of areas orspaces 52 which are defined by the baille members 5|. In this Way,surging of the etching acid or fluid due to the vertical movement of theplunger 31 is eliminated.

When the plate to be etched has been treated in the present apparatus,it is found upon removing the plate therefrom that the etched surface isvery cleanly etched and the etched areas are sharply defined. This isindicated in the section (Fig. 12) which is an enlarged, somewhatschematic View of a portion of a plate etched in the present machine.The view is typical of the dot formation on the etched plate in that thetop portion of the dots is parallel to the bottom of the etched portionsof the plate and each dot appears as a small, substantially cylindricalelement which is secured to the plate. The channels between the dots aresubstantially straight sided and there is a substantially sharp line ofjuncture between the dots and the plate. In this way plates etched inthe present machine eX- hibit properties not found in plates etched inother types of mechanical etching devices.

The clean sharp etching which results from the use of the machineembodying the present invention is due to two factors. First, as shownin Fig. 5, the plate to be etched 49 is at all times submerged in theacid. The movement of the plate horizontally through the acid causes allportions of the plate to be brought in contact with the acid at alltimes. .The acid itself is agitated by the action of the perforatedplunger 31 and as the plunger 31 moves vertically in the tank relativeto the plate 49, a constant ow of acid is provided. During thedownstroke of the plunger 31, the acid is brought forcibly in contactwith the face of the plate 49 and as the plunger 31 moves in theopposite direction, there is a drawing away or suction effect whichcauses the acid to be drawn away from the face of the plate 49. Thus,the acid is constantly circulating and fresh acid is continuallybeinggbrought into contact with the plates 49 and the exhausted acidcarrying the salts of the etching reaction is drawn out of and away fromthe plate 49. In this way, the salts of the reaction do not block outthe subsequent action of the etching acid as is the case in manyconventional etching machines where a continuous spraying or splashingof the acid onto the surface of the plate is employed.

While I have described particular means of effecting the movements ofthe plate and the plunger relative to one another, it is to beunderstood that other types of mechanisms may be employed for the samepurpose.

In the course of my experiments I have found that it is preferable thatthe openings between the strands of material forming the perforatedplunger 31 should comprise approximately 40% of the total area of theplunger. Instead of the crossed strands as shown in Fig. 4, the plungeralso may be formed of pierced or perforated sheets of metal or othermaterials or they maybe formed of parallel strips of metal, wire, Woodor the like which are given suitable acid-proof covering.

I claim:

l. An etching machine comprising a tank, la plate carrier mounted forreciprocating horizontal movement therein, a plunger mounted forreciprocating vertical movement in said tank, and means for moving saidplate carrier and said plunger.

2. An etching machine comprising a tank, a =plate carrier mounted tohold a plate to .be etched below the acid level in said tank and to movesaid plate horizontally therein, a plunger mounted for reciprocatingvertical movement in said tank, and means for moving said plate carrierand said plunger.

3. An etching machine comprising a tank, a plate carrier mounted forreciprocating horizontal movement therein, a perforated plunger mountedfor reciprocating movement in said tank, and means for moving said platecarrier and said plunger.

4. An etching machine comprising a tank, a plate carrier mounted forreciprocating vertical movement therein and adapted to hold a plate tobe etched below the acid level in said tank, .a perforated plungermounted for reciprocating vertical movement in the acid in said tank,and means for moving said plate carrier and said plunger.

5. An etching machine comprising a tank, a plate carrier mounted forreciprocating horizontal movement therein, la perforated plungercomprising crossed metal members secured to a frame and provided with anacid resisting -covering and mounted for reciprocating vertical movementin said tank, and means for moving said plate carrier and said plunger.

6. An etching machine comprising a tank, a plate carrier mounted forreciprocating horizontal movement therein, a plunger mounted forreciprocating vertical movement in said tank, and means for moving saidplate carrier and said plunger at different speeds.

7. An etching machine comprising a tank, a platecarrier mounted forreciprocating horizontal movement therein, a perforated plungercomprising crossed metal members secured to a frame and provided with anacid resisting covering and mounted for reciprocating vertical movementin said tank, and means for moving said plate carrier and said plungerat different speeds.

8. An etching machine comprising a tank, a plate carrier mounted forreciprocating horizontal movement therein, a perforated plungercomprising Icrossed metal members secured toa frame and provided with anacid resisting covering, the openings between said crossed metal memberscomprising approximately 40% of the total area of said plunger, saidplunger being mounted for reciprocating vertical movement in said tank,and means for moving said plate lcarrier and said plunger.

9. An etching machine comprising a tank, a plate carrier mounted forreciprocating horizontal movement therein, a perforated plungercomprising .crossed metal members secured to a frame and provided withan acid resisting covering, the openings between said crossed metalmembers comprising approximately 40% of the total area of said plunger,said plunger being mounted for reciprocating vertical movement in saidtank, and means for moving said plate carrier and said plunger atdifferent speeds.

10. .An etching machine comprising a tank, a plate carrier mounted forreciprocating horizontal movement therein, a perforated plungercomprising crossed metal members secured to a frame and provided with anacid resisting covering, the openings between said crossed metal memberscomprising approximately 40% of the total area of said plunger, saidplunger being mounted for reciprocating vertical movement in said tank,and common means for moving said plate carrier and said plunger atdifferent speeds.

RAYMOND ALBERT ERZ.

